(* completion.sml *)

(* Copyright (C) 2006 Alley Stoughton

   This file is part of crypto, a cryptogram encoder/decoder.  See the
   file COPYING.txt for copying and usage restrictions *)

structure Completion :> COMPLETION =
struct

datatype result =
           None
         | Unique of string
         | Ambiguous

fun complete xs y =
      case List.filter (String.isPrefix y) (StringSet.toList xs) of
           nil => None
         | [z] => Unique z
         | _   => Ambiguous

end;